After an interim period of inactivity based on a select alternative commercial focus, and after consultation with the FDA, Neoprobe Corporation is rapidly reinitiating efforts to develop and commercialize 125Iodine-labeled HuCC49?CH2 anti-Tumor Associated Glycoprotein-72 (TAG-72) monoclonal antibody construct as an aid to cancer surgeons who are operating on patients to remove liver tumors that have spread or metastasized from adenocarcinomas of the colon or rectum. TAG-72 is an adenocarcinoma specific product with both notable production in the tumor center and strong tumor margin definition. HuCC49?CH2 binds to TAG-72 with very high affinity and specificity. When 125I-HuCC49?CH2 binds to TAG-72, it emits a radioactive signal that can be detected a handheld gamma detection probe utilized by the surgeon. This signal, defined in real time during the surgery, informs the surgeon as to the location and extent of the cancer that the surgeon is trying to remove. This will assist the surgeon in two ways that will provide benefit to the patient and improve their quality of care. First, it will help the surgeon remove the entire tumor from the liver and avoid leaving small amounts of cancer at the margins of the surgical resection. Second, it will permit surgeons identify small, difficult to identify or occult tumors that may hav spread beyond the liver, especially to nearby or perihepatic lymph nodes that drain the tumor area. To complete the development and commercialization of 125I-HuCC49?CH2 for the intended use described, Neoprobe must complete a preclinical testing bridging study packet and two human clinical trials. The product studies involving validation of chemistry, manufacturing, and controls (CMC) studies have already been initiated and are near completion. The FDA does require a bridging packet of preclinical animal studies. The purpose of these preclinical animal studies is to show that the current production lots of 125I-HuCC49?CH2 are equivalent to the lots of diagnostic drug used previously. After the CMC and preclinical studies are completed, Neoprobe will perform an FDA requested standardization clinical trial that will examine product safety and will train surgeons on the use of 125I-HuCC49?CH2 for the intended use in radioimmunoguided surgery (RIGS) and harmonize surgical procedures. This standardization trial will set the stage for a pivotal Phase 3 clinical trial of the product demonstrating the safey and efficacy of the 125I-HuCC49?CH2/RIGS system and will support an NDA application to the FDA seeking permission to market the product for use in liver metastases of adenocarcinomas of the colon and rectum. Neoprobe is seeking SBIR Fast Track grant support for part of the required preclinical animal study effort and for the standardization clinical trial.